The invention relates to a thin film magnetic head, a head gimbals assembly, a head arm assembly, and a magnetic disk unit each including a magnetic read head section and a magnetic write head section.
A magnetic disk unit has been used for writing and reading magnetic information (hereinafter, simply referred to as information). The magnetic disk unit may include, for example, in a housing thereof, a magnetic disk in which information is stored, and a thin film magnetic head that writes information into the magnetic disk and reads information stored in the magnetic disk. The magnetic disk is supported by a rotary shaft of a spindle motor, which is fixed to the housing, and rotates around the rotary shaft. In contrast, the thin film magnetic head is formed on a side surface of a magnetic head slider that is provided on one end of a suspension, and includes a magnetic write element and a magnetic read element that have an air bearing surface (ABS) facing the magnetic disk. In particular, as the magnetic read element, a magnetoresistive (MR) element exhibiting MR effect is generally used. The other end of the suspension is attached to a tip end of an arm that is supported and allowed to pivot by a fixed shaft that is installed upright inside the housing.
When the magnetic disk unit is in a stationary state, namely, when the magnetic disk does not rotate and remains stationary, the ABS of the thin film magnetic head is in contact with a surface of the magnetic disk while being lightly pressed against the surface by energization force of the suspension. When the magnetic disk unit is driven and the magnetic disk starts to rotate, the magnetic head slider slightly floats to form a fine spacing (magnetic spacing) between the ABS and the surface of the magnetic disk. Stabilizing the floating amount makes it possible to perform accurate writing and reading of information.
Incidentally, in recent years, along with a progress in higher recording density (higher capacity) of the magnetic disk, reduction in recording track width is progressing. Such reduction in recording track width results in reduction in the size of the thin film magnetic head. Thus, signal recording performance of the magnetic write element on the magnetic disk is weakened and intensity of signal magnetic field from the magnetic disk is weakened as well. To compensate deterioration of these functions, it may be necessary to reduce the size of the magnetic spacing (bring the ABS of the thin film magnetic head closer to the surface of the magnetic disk).
Thus, when the floating height of the entire magnetic head slider is reduced, sufficient control is not performed, which causes the thin film magnetic head to contact a fine projection or any other thing on the surface of the magnetic disk. This may disadvantageously cause occurrence of an abnormal signal due to heat generation and abrasion of the thin film magnetic head itself.
To solve such an issue, the applicant has proposed a thin film magnetic head in which a heating means is provided on an opposite side of a magnetic conversion element from the ABS (refer to Japanese Unexamined Patent Application Publication No. 2003-168274). The magnetic conversion element is configured of a magnetic write element and a magnetic read element. In the thin film magnetic head, in driving of a magnetic disk unit, thermal expansion of surrounding parts of a heating element that is caused by heat generated by the heating element is used to cause the magnetic conversion element to protrude toward the ABS side, thereby achieving minute magnetic spacing. At this time, the heat generation amount is controlled to adjust a degree of the protrusion with high accuracy, and even the minute magnetic spacing is stably maintained. Thus, probability that a surface of a magnetic disk is brought into contact with the thin film magnetic head is considerably reduced.
Further, after the disclosure of the above-described thin film magnetic head, a thin film magnetic head has been proposed in which a temperature detection section is mounted and an amount of a current supplied to a heating element is controlled based on detected temperature information (for example, refer to Japanese Unexamined Patent Application Publication No. 2003-272335). In the thin film magnetic head, a pair of heating elements are so provided as to sandwich a magnetic conversion element along a rotation direction of a magnetic disk, and the temperature detection section is provided between one of the heating elements and the magnetic conversion element. In addition, as relevant prior art, a magnetic disk unit has been disclosed in which a magnetic head slider including a heating element and an arm provided with a temperature sensor are provided (for example, refer to U.S. Pat. No. 5,991,113). Also, a magnetic head slider in which two heaters are provided in one layer close to a thin film magnetic head has been disclosed in Japanese Unexamined Patent Application Publication No. 2008-165950. Furthermore, a magnetic head slider including a heater disposed near a read element has been disclosed in Japanese Unexamined Patent Application Publication No. 2007-280502.